Method and system facilitating paging a user equipment

ABSTRACT

Disclosed are systems and methods that include embodiments to determine a system frame number (SFN) of a radio frame using a first identifier related to the UE, a discontinuous reception (DRX) period length of the UE, and a parameter indicating a quantity of paging occasions within the DRX period length. A second identifier can be sent in a downlink control channel within a radio sub-frame of the radio frame, and a paging message is associated with the second identifier. This systems and methods may also include embodiments to determine a position of the radio sub-frame within the radio frame associated with the SFN with reference to a quantity of radio sub-frames suitable for the paging in the radio frame, the identifier related to the UE, and a parameter derived from the DRX period length of the UE.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/964,370, filed on Aug. 12, 2013, which is a continuation of U.S.patent application Ser. No. 12/793,480, filed on Jun. 3, 2010, now U.S.Pat. No.8,543,140, which is a continuation of International ApplicationNo. PCT/CN2008/073204, filed on Nov. 26, 2008, which claims priority toChinese Patent Application No. 200710077484.X, filed on Dec. 3, 2007.The afore-mentioned patent applications are hereby incorporated byreference in their entireties.

TECHNICAL FIELD

The present disclosure relates to the mobile communications field, andin particular, to a method and an apparatus for determining paging time.

BACKGROUND

The Universal Mobile Telecommunications System (UMTS) is a radiocommunications network technology standard defined by the 3rd GenerationPartnership Project (3GPP) organization.

In UMTS, a basic process of paging is related to two channels: a PagingIndication Channel (PICH), and a Paging Channel (PCH). The PICH is afixed-rate physical channel (with the spread factor being 256), and thePICH is elaborated in 3GPP TS25.211 v4.2.0. FIG. 1 shows a framestructure of the PICH. The length of a PICH radio frame is 10 ms, whichis composed of 300 bits. Of those bits, 288 bits (b0, b1, . . . , b287)bear the Paging Indication (PI), and the remaining 12 bits are reservedfor future use and are not sent. One PI is composed of several bits.Depending on the length of one PI, each PICH frame may bear 18, 36, 72,or 144 PIs. The quantity of PIs carried in one PICH frame is denoted byNp. A Secondary Common Control Physical Channel (SCCPCH) bears the PCH.The PCH carries the specific content of the paging message, for example,User Equipment (UE) Identifier (ID), paging cause, and Circuit Switched(CN) domain ID. The PICH is correlated with the SCCPCH. A tail of thePICH radio frame is ahead of the SCCPCH correlated with PICH radio frameby 7680 chips.

FIG. 2 shows UE paging in a UMTS in the prior art.

After registering with a network, the UE is assigned to a paging group.Each paging group has a corresponding PI. When the UE in the paginggroup is paged, the PI corresponding to the paging group appears on thePICH periodically. After detecting the PI on the PICH, the UE startsreceiving the specific paging message from the PCH through the SCCPCH.The upper layer of the protocol of the UE interprets the paging message.

The UE receives information in Discontinuous Reception (DRX) mode.Through the DRX mode, the UE is in a sleep mode when it is in an idlemode, and thus the power consumption is low. When the UE detects a PI ofthe UE, the UE awakens to receive the specific paging message. The UEmonitors the PI periodically. If the period for monitoring the PI islonger, the chance for the UE to awaken is slim, and the UE is moreenergy-efficient. The UE, however, slowly responds to the networkpaging.

In UMTS, the UE obtains the content of the paging message in threesteps:

Step 1. A System Frame Number (SFN) that includes the paging occasion isdetermined.

k indicates CN domain-specific DRX Cycle Length coefficient of the UEand the value range is 6≦k≦9; and a Paging Block Period (PBP) rangesfrom 4 to 64 in a TDD mode, and the PRB is 1 in the FDD mode. Therefore,in the idle mode, the DRX Cycle Length is calculated through Formula2.1, and is expressed in radio frames.

DRX Cycle Length=max(2^(k), PBP)   Formula 2.1

Further, the SFN that includes the paging occasion of the UE iscalculated through Formula 2.2.

SFN={(IMSI div M)mod(DRX Cycle Length div PBP)}*PBP+n*DRX CycleLength+Frame Offset    Formula 2.2

In the above Formula 2.2, M is the quantity of SCCPCHs that bear thePCHs; Frame Offset is the offset of the frame, which is 0 in the FDDmode; n is a non-negative integer, and the value of n is acceptable onlyif the calculated value of SFN is less than the maximum value 4095 ofthe SFN allowed by the system.

Step 2. A position of the PI to be decoded in the radio frame isdetermined.

The position of the PI in the radio frame is calculated through Formula2.3 and Formula 2.4 according to an International Mobile SubscriberIdentifier (IMSI) and a DRX Index of the UE.

Formula 2.3   Formula 2.3

PI=DRX index mod Np   Formula 2.4

The UMTS employs an SFN-based glide mechanism to calculate the actualposition (q) of the PI in the radio frame more precisely. Thecalculation of the position (q) is performed through Formula 2.5. TheSFN changes with time. The position (q) of the PI glides with the changeof the SFN.

$\begin{matrix}{q = \left( {{P\; I} + {\left\lfloor \left( \begin{matrix}\left( {18 \times \left( {{SFN} + \left\lfloor {{SFN}/8} \right\rfloor + \left\lfloor {{SFN}/64} \right\rfloor +} \right.} \right. \\{\left. {\left. \left. \left\lfloor {{SFN}/512} \right\rfloor \right) \right)\; {mod}\; 144} \right) \times \frac{Np}{144}}\end{matrix} \right\rfloor \right)\; {mod}\mspace{11mu} {Np}}} \right.} & {{Formula}\mspace{14mu} 2.5}\end{matrix}$

Step 3. The PCH is read to obtain the specific content of the UE pagingmessage.

Pq denotes the value of the PI in the position q. If Pq=0, it indicatesthat the PI is invalid, and the UE dose not need wakeup. If Pq=1, itindicates that the PI is valid, and the UE needs wakeup. According tothe corresponding position relation between the PICH and the SCCPCH thatbears the PCH, the specific content of the paging message is read.

As described above, in UMTS, the UE calculates the SFN that includes thepaging according to the IMSI and the DRX Index, and uses Np to calculatethe actual position (for example, bit position or bit group position) ofthe PI to be decoded in the radio frame. The UE reads the PCH accordingto the corresponding position relation between the PICH and the SCCPCHthat bears the PCH, and obtains the specific content of the UE pagingmessage.

Meanings of the symbols involved in the foregoing formula (applicable tothe following text) are: mod means modulo operation, div means divisionand round-off, └ ┘ means round-down, and max(a, b) means a greater valueamong a and b.

A Long Term Evolution (LTE) project is intended for the mobilecommunication architecture to be developed by the 3GPP organization inthe coming 10 years. FIG. 3 shows a structure of a radio frame appliedin LTE. One frame is 10 ms, and is composed of 10 radio sub-frames, witheach radio sub-frame being 1 ms. One radio sub-frame includes twotimeslots, namely, each timeslot is 0.5 ms.

FIG. 4 shows a structure bearer of a radio sub-frame applied in LTE. Oneradio sub-frame includes 14 Orthogonal Frequency Division Multiplexing(OFDM) symbols, where the first three OFDM symbols bear the PhysicalDownlink Control Channel (PDCCH), and the last 11 OFDM symbols bear thePhysical Downlink Shared Channel (PDSCH). The PDCCH bears the PagingRadio Network Temporary Identifier (P-RNTI), and the PCH mapped onto thePDSCH bears the specific content of the paging message.

The prior art described above reveals that: Compared with UMTS, LTE doesnot define PICH or PI, but defines a PCH for bearing the paging content.Meanwhile, the channel bearer unit changes from the 10-ms radio frame tothe 1-ms radio sub-frame. There are many other systems like the LTEwhose physical channel type and structure are different from those ofthe UMTS. In such systems, the computation of the paging occasion inUMTS in the prior art is not applicable any more, and such systems areunable to determine the paging time.

SUMMARY

According to a first aspect of the disclosure, a method for facilitatingpaging a UE is disclosed. A network device sends a P-RNTI to the UE in aPDCCH within a radio sub-frame of a radio frame. A paging message isassociated with the P-RNTI. The UE determines a system frame number(SFN) of the radio frame by consideration of parameters including aparameter related to an identifier of the UE, a Discontinuous Reception(DRX) period length of the UE, and a parameter indicating a quantity ofpaging occasions within the DRX period length. The UE determines aposition of the radio sub-frame within the radio frame, obtains theP-RNTI in the PDCCH within the radio sub-frame, and obtains the pagingmessage associated with the P-RNTI.

According to a second aspect of the disclosure, a system is disclosed.The system includes a UE in communication with a network device. Thenetwork device is configured to send a P-RNTI to the UE in a PDCCHwithin a radio sub-frame of a radio frame. A paging message isassociated with the P-RNTI. The UE is configured to determine a systemframe number (SFN) of the radio frame by consideration of parametersincluding a parameter related to an identifier of the UE, aDiscontinuous Reception (DRX) period length of the UE, and a parameterindicating a quantity of paging occasions within the DRX period length.The UE is further configured to determine a position of the radiosub-frame within the radio frame, obtain the P-RNTI in the PDCCH withinthe radio sub-frame, and obtain the paging message associated with theP-RNTI.

According to a third aspect of the disclosure, a method for facilitatingpaging a UE is disclosed. The UE receives a P-RNTI. The P-RNTI is sentby a network device to the UE in a PDCCH within a radio sub-frame of aradio frame. A paging message is associated with the P-RNTI. The UEdetermines a system frame number (SFN) of the radio frame byconsideration of parameters including a parameter related to anidentifier of the UE, a Discontinuous Reception (DRX) period length ofthe UE, and a parameter indicating a quantity of paging occasions withinthe DRX period length. The UE determines a position of the radiosub-frame within the radio frame; obtains the P-RNTI in the PDCCH withinthe radio sub-frame; and obtains the paging message associated with theP-RNTI.

According to a fourth aspect of the disclosure, a UE is disclosed. TheUE includes a memory retaining instructions and a processor. Theprocessor is coupled to the memory, and is configured to execute theinstructions retained in the memory. The instructions relate to thethird aspect of the disclosure.

According to a fifth aspect of the disclosure, a method for facilitatingpaging a UE is disclosed. A network device determines a P-RNTI. A pagingmessage is associated with the P-RNTI. The network device determines asystem frame number (SFN) of a radio frame by consideration ofparameters including a parameter related to an identifier of the UE, aDiscontinuous Reception (DRX) period length of the UE, and a parameterindicating a quantity of paging occasions within the DRX period length.The network device determines a position of a radio sub-frame within theradio frame; and sends the P-RNTI to the UE in a PDCCH within the radiosub-frame of the radio frame.

According to a sixth aspect of the disclosure, a network device isdisclosed. The network device includes a memory retaining instructionsand a processor. The processor is coupled to the memory, and isconfigured to execute the instructions retained in the memory. Theinstructions relate to the fifth aspect of the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a structure of a PICH radio frame in a UMTS system;

FIG. 2 shows UE paging in a UMTS system;

FIG. 3 shows a radio frame structure applied in an LTE system;

FIG. 4 shows a radio sub-frame structure bearer applied in an LTE systemin the prior art;

FIG. 5 shows paging time in an embodiment of the present disclosure; and

FIG. 6 shows paging time in another embodiment of the presentdisclosure.

DETAILED DESCRIPTION

The technical solution under the present disclosure is expounded belowwith reference to the accompanying drawings. The embodiments describedherein are only part of the embodiments of the present disclosure. Thoseskilled in the art can derive other embodiments from the embodimentsdescribed herein without making any creative effort, and all suchembodiments are meant to be encompassed by the scope of the claimssubmitted herewith.

At the network side, the network device sends a paging identifier (e.g.,P-RNTI) and a paging message to a specific UE at specific time (namely,specific radio sub-frame). The specific time can be calculated accordingto the UE identifier, the DRX period length of the UE, quantity ofpaging occasions within the DRX period, and the quantity of radiosub-frames for paging in one radio frame.

At the user side, the UE decodes the specific radio sub-frame to obtainthe paging message in the same way as the operation at the network side.Specifically, the UE in the idle state decodes the PDCCH at the specifictime (namely, specific radio sub-frame). If the P-RNTI over the PDCCH isobtained, it indicates that a paging message exists, and the UE awakensand decodes the PDSCH radio sub-frame that bears the specific pagingcontent to finally obtain the paging content. The UE under the presentdisclosure uses the DRX mode to accomplish energy efficiency of the UE.

In the embodiments of the present disclosure, paging occasion refers tothe position (namely, SFN) of the radio frame that includes the pagingmessage in the DRX period, and paging time means the position of theradio sub-frame that includes the paging identifier.

FIG. 5 shows paging time in an embodiment of the present disclosure. Atthe network side, the SFN of radio frames ranges from 0 to 4095.Specifically, the SFN of the radio frame subsequent to the radio framenumbered “SFN 4095” is 0. The DRX period length of the network side isnot less than 2^(k) frames (3≦k≦9). As shown in FIG. 5, when k is 3, theDRX period length is 8. Both the radio frame numbered “SFN 0” and theradio frame numbered “SFN 8” correspond to the paging occasion. Takingthe radio frame numbered “SFN 8” as an example, the paging occasion islocated on the radio sub-frame numbered 4 and the radio sub-framenumbered 7.

The UE calculates the paging time in the following steps:

1. The paging occasion (SFN of radio frame) is determined.

RAGING_DRX_PERIOD indicates the DRX period length of the UE. If thevalue of PAGING_DRX_PERIOD is specified by the network uniformly, the UEmay read the value from a network broadcast when the UE resides onto acell. If the value is specified by the network for a specific UE, thenetwork tells the value to the UE through signaling.

UE_ID indicates a UE identifier. The UE identifier may be an IMSIwritten into the SIM card of the UE, an IMSI-related ID (such as IMSImod X, where X is a positive integer), or a

Temporary Mobile Station Identifier (TMSI) allocated by the core networkto the UE when the UE is attached to the network.

PAGING_OCCASION_NUMBER indicates the quantity of paging occasions of theUE within the DRX period.

Frame Offset indicates offset of a frame, and is a non-negative integernot greater than the maximum value of the SFN of the radio frame.

M indicates the quantity of radio sub-frames suitable for paging in oneradio frame. M is a non-negative integer not greater than the quantityof radio sub-frames in one radio frame. For example, in an LTE system,the quantity of radio sub-frames in a radio frame is 10 (0≦M≦10).Especially, if the value of M is 0, it indicates that no radio sub-framefor paging exists in the radio frame. M is set by the system. When theUE enters the cell, M may be read and obtained from the networkbroadcast.

Therefore, the paging occasion may be determined according to Formula5.1.1 or Formula 5.1.2. n is a non-negative integer which makes thecalculated SFN value not greater than the maximum SFN value.

SFN=(RAGING_DRX_PERIOD div PAGING_OCCASION_NUMBER)*(UE_ID modPAGING_OCCASION_NUMBER)+n*PAGING_DRX_PERIOD+Frame Offset    Formula5.1.1

SFN={(UE_ID div M)mod(PAGING_DRX_PERIOD divPAGING_OCCASION_NUMBER)}*PAGING_OCCASION_NUMBER+n*RAGING_DRX_PERIOD+FrameOffset    Formula 5.1.2

2. The paging time (radio sub-frame position q) is determined.

The DRX Index may be calculated through Formula 5.2.

DRX Index=IMSI div Y   Formula 5.2

Y is a parameter. The value of Y may be specified by the network in viewof the performance indices. For example, taking LTE as an example, thenetwork may specify the value of Y to be 8192, or another value greaterthan 2⁹. The value of Y may also be calculated according to the M andthe DRX period length. In different systems, the M and the DRX periodlength may have different values. Taking the LTE system as an example,when the maximum value of M is 10 and the maximum value of the DRXperiod length is 2⁹, then:

Y=M _(max)*RAGING_DRX_PERIOD_(max)=2⁹*10=5120.

Further, the paging time may be determined through Formula 5.3 accordingto the DRX Index and the M.

q=DRX Index mod M   Formula 5.3

In this embodiment, the UE determines the paging occasion first, namely,the position of the radio frame that includes the P-RNTI, and thendetermines the paging time, namely, the position of the radio sub-framethat includes the P-RNTI. With this method, the UE needs to decode onlyone radio sub-frame, without the need of decoding the whole radio frame.The paging time can be determined and the UE is more energy-efficient.

It is understandable to those skilled in the art that the paging timedetermined by the network needs to be consistent with the paging timedetermined by the UE. For the network side, the parameters involved inthis embodiment can be configured or obtained. Therefore, the method ofdetermining the paging time in this embodiment is applicable to thenetwork-side device as well.

FIG. 6 shows paging time in another embodiment of the presentdisclosure. At the network side, the SFN of radio frames ranges from 0to 4095. Specifically, the SFN of the radio frame subsequent to theradio frame numbered “SFN 4095” is 0. The DRX period length of thenetwork side is not less than 2^(k) frames (3≦k≦9). As shown in FIG. 6,the paging time is located in the radio sub-frame numbered 4 and theradio sub-frame numbered 7. The foregoing two radio sub-frames arelocated in the radio frame whose SFN is n.

The UE calculates the paging time, namely, determines the radiosub-frame position “Sub-frame Index” in the following process:

PAGING_DRX_PERIOD denotes the DRX period of the UE.

UE_ID indicates a UE identifier. The UE identifier may be an IMSIwritten into the SIM card of the UE, an IMSI-related ID (such as IMSImod X, where X is a positive integer), or a TMSI allocated by the corenetwork to the UE when the UE is attached to the network.

PAGING_OCCASION_NUMBER indicates the quantity of paging occasions of theUE within the DRX period.

Q is the quantity of radio sub-frames in a radio frame. In an LTEsystem, the value of Q is 10.

Sub-frame Offset indicates offset of a radio sub-frame, and is anon-negative integer not greater than (4096*Q−1).

Therefore, the paging time may be determined through Formula 6.1. n is anon-negative integer which makes the calculated Sub-frame Index valuenot greater than the maximum SFN value (namely, 4096*Q−1) allowed by thesystem.

Subframe Index=(PAGING_DRX_PERIOD*Q div PAGING_OCCASION_NUMBER)*(UE_IDmod PAGING_OCCASION_NUMBER)+n*PAGING_DRX_PERIOD*Q+Subframe Offset  Formula 6.1

In this embodiment, the UE may determine the paging time directly,namely, the position of the radio sub-frame that includes the P-RNTI.Optionally, the UE may further determine the paging occasion, namely,the position of the radio frame that includes the P-RNTI, and thendetermine the position of the foregoing radio sub-frame moreconveniently. The UE may determine the paging occasion through Formula6.2. Frame Offset indicates offset of a frame, and is a non-negativeinteger not greater than the maximum SFN value.

SFN=Subframe Index div Q+Frame Offset   Formula 6.2

In this embodiment, the UE needs to decode only one radio sub-frame,without the need of decoding the whole radio frame. The paging time canbe determined and the UE is more energy-efficient.

It is understandable to those skilled in the art that the paging timedetermined by the network needs to be consistent with the paging timedetermined by the UE. For the network side, the parameters involved inthis embodiment can be configured or obtained. Therefore, the method ofdetermining the paging time in this embodiment is applicable to thenetwork-side device as well.

Although the foregoing description quotes some parameters andcommunication concepts in the LTE, the present disclosure is applicableto multiple systems on the whole so long as a PCH for bearing pagingexists in the system and the radio frame is composed of at least oneradio sub-frame.

Although the disclosure has been described through preferred exemplaryembodiments, the disclosure is not limited to such embodiments. It isapparent that those skilled in the art can make modifications andvariations to the disclosure without departing from the scope of thedisclosure. The disclosure is intended to cover the modifications andvariations provided that they fall in the scope of protection defined bythe following claims or their equivalents.

What is claimed is:
 1. A method for paging a user equipment (UE),comprising: determining a system frame number (SFN) of a radio frameusing a first identifier related to the UE, a discontinuous reception(DRX) period length of the UE, and a parameter indicating a quantity ofpaging occasions within the DRX period length, wherein a secondidentifier is sent in a downlink control channel within a radiosub-frame of the radio frame, and a paging message is associated withthe second identifier; determining a position of the radio sub-framewithin the radio frame associated with the SFN with reference to aquantity of radio sub-frames suitable for the paging in the radio frame,the identifier related to the UE, and a parameter derived from the DRXperiod length of the UE.
 2. The method of claim 1, wherein the firstidentifier related to the UE comprises an-international mobilesubscriber identifier (IMSI) of the UE.
 3. The method of claim 1,wherein the first identifier related to the UE comprises an IMSI of theUE mod a positive integer.
 4. The method of claim 1, wherein the secondidentifier is paging radio network temporary identifier (P-RNTI).
 5. Themethod of claim 1, wherein the SFN of the radio frame is determinedaccording to the following formula:SFN=(RAGING_DRX_PERIOD div PAGING_OCCASION_NUMBER)*(UE_ID modPAGING_OCCASION_NUMBER)+n*RAGING_DRX_PERIOD+Frame Offset wherein the SFNis the SFN of the radio frame, the RAGING_DRX_PERIOD indicates the DRXperiod length of the UE, the PAGING_OCCASION_NUMBER is the parameterindicating a quantity of paging occasions within the DRX period length,the UE_ID is the parameter related to an identifier of the UE, the n isa non-negative integer, and the Frame Offset is a non-negative integer.6. The method of claim 4, further comprising: sending, by a networkdevice, the P-RNTI to the UE in the PDCCH within the radio sub-frame ofthe radio frame.
 7. The method of claim 1, further comprising: decoding,by the UE, the downlink control channel within the radio sub-frame. 8.An communication system, wherein the system comprising an user equipment(UE) which is in communication with a network device, wherein the UE isconfigured to: determine a system frame number (SFN) of a radioframeusing parameters including a first identifier related to the UE, adiscontinuous reception (DRX) period length of the UE, and a parameterindicating a quantity of paging occasions within the DRX period length,wherein a second identifier is sent in a downlink control channel withina radio sub-frame of the radio frame, and a paging message is associatedwith the second identifier; determine a position of the radio sub-framewithin the radio frame associated with the SFN with reference to aquantity of radio sub-frames suitable for the paging in the radio frame,the identifier related to the UE, and a parameter derived from the DRXperiod length of the UE; and decode the downlink control channel withinthe radio sub-frame.
 9. The system of claim 8, wherein the firstidentifier related to the UE comprises an international mobilesubscriber identifier (IMSI) of the UE.
 10. The system of claim 8,wherein the first identifier related to the UE comprises an IMSI of theUE mod a positive integer.
 11. The system of claim 8, wherein the DRXperiod length of the UE is a DRX value being specific for the UE. 12.The system of claim 8, wherein the second identifier is paging radionetwork temporary identifier (P-RNTI).
 13. The system of claim 8,wherein the SFN of the radio frame is determined according to thefollowing formula:SFN=(RAGING_DRX_PERIOD div PAGING_OCCASION_NUMBER)*(UE_ID modPAGING_OCCASION_NUMBER)+n*PAGING_DRX_PERIOD+Frame Offset wherein the SFNis the SFN of the radio frame, the RAGING_DRX_PERIOD indicates the DRXperiod length of the UE, the PAGING_OCCASION_NUMBER is the parameterindicating a quantity of paging occasions within the DRX period length,the UE_ID is the parameter related to an identifier of the UE, the n isa non-negative integer, and the Frame Offset is a non-negative integer.14. The system of claim 13, wherein the Frame Offset is set to
 0. 15. Ancommunication system, wherein the system comprising network device whichis in communication with a user equipment (UE), wherein the networkdevice is configured to: determine a system frame number (SFN) of aradio frame using parameters including a first identifier related to theUE, a discontinuous reception (DRX) period length of the UE, and aparameter indicating a quantity of paging occasions within the DRXperiod length, wherein a second identifier is sent in a downlink controlchannel within a radio sub-frame of the radio frame, and a pagingmessage is associated with the second identifier; determine a positionof the radio sub-frame within the radio frame associated with the SFNwith reference to a quantity of radio sub-frames suitable for the pagingin the radio frame, the identifier related to the UE, and a parameterderived from the DRX period length of the UE; and send the secondidentifier to the UE in the downlink control channel within the radiosub-frame of the radio frame.
 16. The system of claim 15, wherein theidentifier related to the UE comprises an-international mobilesubscriber identifier (IMSI) of the UE.
 17. The system of claim 15,wherein the identifier related to the UE comprises an IMSI of the UE moda positive integer.
 18. The system of claim 15, wherein the DRX periodlength of the UE is a DRX value being specific for the UE.
 19. Thesystem of claim 15, wherein the SFN of the radio frame is determinedaccording to the following formula:SFN=(RAGING_DRX_PERIOD div PAGING_OCCASION_NUMBER)*(UE_ID modPAGING_OCCASION_NUMBER)+n*RAGING_DRX_PERIOD+Frame Offset wherein the SFNis the SFN of the radio frame, the RAGING_DRX_PERIOD indicates the DRXperiod length of the UE, the PAGING_OCCASION_NUMBER is the parameterindicating a quantity of paging occasions within the DRX period length,the UE_ID is the parameter related to an identifier of the UE, the n isa non-negative integer, and the Frame Offset is a non-negative integer.20. The system of claim 15, the wherein the second identifier is pagingradio network temporary identifier (P-RNTI).